<?php

$bool = true;
$bool = TRUE;
$bool = false;
$bool = FALSE;

$num = 45345;

$num1 = 45.4545454;

$str = "学\"并\"思";
$str = '学\'并\'思';



$str = "学{$num}并思";
$str1 = '学并思$num';

$str = <<<bbb

用户名：<input type="text" id='df'>
		密码：<input type='text' class="dfdf">
bbb;

echo $str;

$num = null;

var_dump(gettype($bool));
// var_dump($str);
// var_dump($str1);


// $str = "45656";

// $num = strval($str);
// 
$str = false;

$res = settype($str,'int');

var_dump($res);

var_dump($str);